In GC systems, the amount of time required for a chemical compound to traverse the entire length of a separation column (“column”) is known as its retention time. One factor that contributes to the retention time of a chemical compound is the temperature of the separation column. Controlling the temperature of the column precisely from analysis to analysis is beneficial to provide repeatability in the retention time for a particular chemical compound, or analyte. In addition, programmatically changing the column temperature while the sample analytes are migrating through it can advantageously provide shorter analysis time and reduce peak broadening.
Precise control of the temperature of the column is, of course, important to the overall performance of the GC measurement. In many column temperature control systems, the temperature sensor does not measure the actual column temperature because it is located away from the column for various reasons. Although it is desirable for the column temperature to be constant along its length, no column heating system provides a completely isothermal environment. For the user of the GC apparatus, it is important that the thermal gradients along the length of the GC column are small and that analytes migrating through the column experience an effective temperature that provides the desired retention characteristics.
What is needed, therefore, is an apparatus that overcomes at least the drawbacks of known GC column heaters discussed above.